In a major victory for environmental regulation, the D.C. Court of Appeals unanimously ruled Tuesday to uphold the right of the Environmental Protection Agency to regulate emissions of greenhouse gases.

The Court’s ruling puts an end to a three-year-long suit in which a coalition of states challenged the EPA’s 2009 finding that carbon dioxide emissions endangered public health and should be regulated.

The ruling also affirms the efforts of climate change activists. The Court soundly rejected the challengers’ claim that the environmental risks of greenhouse gases were not conclusively proven. In particular, they bashed claims that the EPA had not provided enough of its own evidence that carbon dioxide is harmful—using some pointed wording.

“This is how science works,” the judges wrote in their unanimous opinion. “The EPA is not required to re-prove the existence of the atom every time it approaches a scientific question.”

The EPA’s challengers—the National Association of Manufacturers, the National Mining Association, and the US Chamber of Commerce and a coalition of states led by Texas and Virginia, brought the suit in response to the EPA’s 2009 finding that carbon dioxide emissions were hazardous and should be regulated. The Court ruled this week that the EPA was “unambiguously correct” in regulating emissions.

Now that the EPA’s right to regulate has been upheld, what limits should gas-emitters expect to see? For emissions from cars and light trucks, there’s the “Tailpipe Rule,” which will set limits on the CO2 emissions from cars and light trucks.

For “stationary sources” of emissions (such as industrial factories and energy plants that burn fossil fuels) regulations will require companies to obtain permits for construction and operation of their facilities. This requirement, which will initially target only the heaviest emitters of greenhouse gases, would go into effect gradually according to the agency’s “Tailoring Rule” determining which industries are subject to the requirement and “Timing Rule” determining when the rule goes into effect for each category of emitter.

(In addition to the plaintiffs’ challenge of the general regulation of greenhouse gases, they also challenged the permit requirement’s timeline for discriminating against certain industries. The Court found that the plaintiffs did not have the standing to challenge the EPA’s rules of timing.)

Despite the burden that these new regulations would place on gas-emitting industries, official opinion among the effected industries is somewhat divided. The National Association of Manufacturers strongly opposes the ruling. But big auto companies—bound by the 2008 auto industry bailout to meet higher fuel-efficiency requirements—have expressed support for regulations. The Alliance of Automobile Manufacturers issued a statement citing the investments that auto companies have made in cleaner emissions in recent years and saying that a unified standard for emissions was among the auto industry’s “top national priorities,” according to The New York Times.

What political effect will this ruling have? It’s a victory for the Obama administration in their push to regulate emissions, and a blow for heavy industries that will have to adjust to the new regulations.

Opponents of regulation say that the tighter rules will hurt industries at a time when they badly need to grow. Representative Fred Upton (R—Mich.), who is chairman of the Committee on Energy and Commerce, told The New York Times that regulation “threatens to drive energy prices higher, destroy jobs and hamstring our economic recovery.” Upton has previously accused the EPA of trying to sidestep Congress by using its regulatory powers to use limits that will impose a new “cap-and-trade”-style policy without congressional legislation.

In 2009 and 2010, Congress debated a bill that would limit carbon dioxide emissions. Its supporters argued that a legislative approach to regulation would be less costly and more efficient than imposing EPA rules. Their regulatory bill passed in the House but died in the Senate.